In electric generators, such as those driven by gas or steam turbines, a tremendous amount of heat may be produced during normal operation. Some generators may weigh hundreds of tons and the unchecked production of heat in such machines as may be caused by mechanical and electrical losses (e.g., I2R losses) may lead to a generator failure. Accordingly, heat dissipation requirements for a generator may be accomplished with a cooling system that utilizes a flow of cooling fluid within the generator housing as well as within the rotor and stator structures to remove the produced heat.
A suite of temperature sensors is provided for the continuous monitoring of the cooling medium and/or generator structures to protect the generator against malfunctions. A rise in temperature may be indicative of malfunctions, such as a damaged winding or reduction in the flow of the cooling fluid due to a partial blockage of a cooling path. U.S. Pat. No. 4,602,872, assigned to the predecessor of the present assignee and herein incorporated by reference, discloses a technique that allows combining the outputs of multiple temperature sensors to obtain an average temperature reading during an initialization process. Each sensor reading is subtracted from the average temperature to derive a correction factor for that particular sensor, for that particular average.
To achieve accurate temperature calibration for any given generator and to avoid erroneous indications, the temperature correction factors should be determined upon achieving stable operational conditions at each of various generator load levels. Written instructions specifying applicable stability criteria for any given generator may be provided to assist the operator to determine whether the generator has reached a sufficient level of stability. In practice, however, it is up to each operator whether to manually verify or simply decide, based on their experience and judgment, when the process for determining the temperature correction factors should be initiated. That is, under present techniques, the initialization process for determining the temperature correction factors may suffer due to the subjectivity and variability that will inevitably occur from one operator to another operator, or even for the same operator over an extended period of time. In addition, a manual verification of operational stability of the generator may require burdensome and time-consuming checks. This is valuable time the operator could put to better use for ensuring smooth and proactive management of the power plant equipment under the responsibility of the operator.